摘要:

Amber-coloured syringes designed for the distribution of unit-doses of oral drops were studied for the efficiency of the photoprotectiveness and the possible binding of eleven phenothiazine neuroleptics: alimemazine, chlorpromazine, cyamemazine, fluphenazine, levomepromazine, periciazine, pipotiazine, prochlorperazine, thioproperazine, thioridazine, and trifluoperazine, all very easily oxidized in solution in daylight. Spectrofluorimetry made it possible, in one operation, to determine the remaining concentrations of drugs after storage and to verify the absence of photo-oxidation. The storage was performed up to 13 days at 25 ± 3°C and without any precaution from daylight. All the drugs studied were stable and none bound on the syringes. However, the stability appeared to be due to the antioxidants in the drug preparations, and not to the coloured material, since oral drops were also stable in uncoloured syringes designed for injection. Nevertheless, the amber-coloured syringes efficiently protect the active principles in pure aqueous solutions, without preservative, and thus this physical protection reinforces the chemical one of the galenical formulation.

ISSN:0920-5063    

DOI:10.1163/156856295X00391

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Microcapsules composed of collagen and chondroitin sulfate were obtained by complex coacervation and characterized by DSC, optical microscopy, SEM, and UV-Vis spectroscopy. Composition of the microcapsules could be adjusted by the feed ratio and the pH of the solutions. Prepared under low temperature and aqueous solution, the process is most suitable for encapsulating delicate bioactive agents. Albumin as a model protein was encapsulated with a loading level of up to 95% by weight. Degradation rate of the microcapsules decreased with the concentration of the crosslinking agent glutaraldehyde and increased with the bacterial collagenase level. Correspondingly the release of albumin could also be varied by the cross-linking degree of the microcapsules.

ISSN:0920-5063    

DOI:10.1163/156856295X00409

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Experimental data from particle electrophoretic measurements of polymer particles have been used for modelling competitive protein adsorption. It could be demonstrated that protein adsorption onto a solid surface is a two-step process: firstly fast reversible adsorption and, secondly, irreversible coupling at the adsorption centres dependent on contact time. The extent of protein competition is influenced by a characteristic time-dependence of the adsorption process. Analysis of the experimental findings results in two models whose corresponding systems of kinetic equations were solved. Both suggested models are based upon relatively simple mechanisms: (a) the parallel reaction; and (b) the exchange reaction. It has been shown that in our experiments a classical exchange process for describing competitive protein adsorption can be very probably supposed.

ISSN:0920-5063    

DOI:10.1163/156856295X00418

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Τhe effects of Tween 20 on the desorption of proteins from polyethylene and polyurethane were studied, using single protein solutions of the human proteins fibrinogen (Fb), immunoglobulin G (IgG), serum albumin (HSA), high density lipoproteins (HDL), and plasma. The surfactant may partly or even completely desorb the proteins, depending on the type of polymer and protein. About 40% of adsorbed HSA and 80% of adsorbed HDL from the corresponding single protein solutions were desorbed by Tween 20 from polyethylene, whereas Tween 20 had a small effect on the desorption of adsorbed Fb and IgG under the same conditions. However, the desorption of Fb and IgG by Tween 20 was much higher in the case of a diluted plasma solution compared to a pure protein solution. These findings may be explained by the differences of the interaction strengths between polymers and the adsorbed proteins. The displacement of HSA from polyethylene by Tween 20 occurred in the first few minutes and did not increase in time. It was also observed that preadsorbed Tween 20 was able to prevent in a large extent the adsorption of HSA onto polyethylene. Thus, the effect of Tween 20 on the desorption of protein is due to either the displacement of protein or prevention of protein adsorption onto the surfaces.

ISSN:0920-5063    

DOI:10.1163/156856295X00427

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The surface characterization of Biomer™ and extracted Biomer™ has been investigated using atomic force microscopy (AFM) in order to show the influence of extraction process on the morphology and local interactions which monitor surface properties at a molecular scale. The high viscoelasticity of these polymers provided by the soft segments makes AFM imaging in contact mode quite difficult, the scanning of the tip inducing artifacts on the surface. The rate, direction, and number of scans strongly influence this friction effect. The recording of force curves has shown that the extraction and conditions of drying can modify the interaction forces present at the polymer surface. Imaging of the extracted Biomer™ obtained with AFM in non-contact mode has revealed inclusion nodules embedded in an amorphous phase. This may be attributed to the migration at the surface of the non-eliminated poly(aminomethacrylate) additive.

ISSN:0920-5063    

DOI:10.1163/156856295X00436

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Based on our research on blood protein interactions with low temperature isotropic carbon (LTIC) and data from the literature, we propose that the carbon surface has strong interactions with adsorbed proteins. In this paper we focus on how a relatively blood-compatible material interacts with plasma proteins. We present our results on the structure and properties of the LTIC surface utilizing SEM, STM, XPS, and contact angle measurements. We briefly review protein adsorption on LTIC using DSC, impedance, radioisotopes, and two-dimensional gel electrophoresis. LTIC is characterized by a microporous, oxidized, hydrophobic, and domain mosaic structure. Surface polishing smoothens the roughness and removes the porosity, while largely destroying the ordered atomic texture, making the surface more random and more amorphous. The LTIC surface denatures all adsorbed proteins studied. The rate of protein adsorption is high and the surface concentration is large. The LTIC surface adsorbs all proteins without preference. The surface also tenaciously retains proteins such that they cannot be displaced by buffer or exchanged by proteins in solution. We conclude that LTIC accomplishes its blood compatibility through a passivating film of strongly adsorbed bland proteins, which do not interact with platelets nor participate in blood coagulation. We also suggest mechanisms for the production of such a film by the LTIC surface.

ISSN:0920-5063    

DOI:10.1163/156856295X00445

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Two quantitative cytotoxicity assay methods (cytoplasmic retention of carboxyfluorescein and mitochondrial cleavage of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT)) have been used to evaluate the response of two cultured human cell lines; HepG2 (hepatoma) and W138va13 (transformed lung fibroblasts) to extracts of a range of poly(vinyl chloride) (PVC) formulations. Two plasticizers; di(2-ethylhexyl)phthalate (DEHP) and di-isooctyl phthalate and a range of tin and non-tin stabilizers were incorporated in the study. Only those formulations containing both a plasticizer and a tin-based stabilizer produced extracts which were toxic. Extracts of those formulations which contained both plasticizer and dibutyl tin dimaleate stabilizer were toxic to both cell lines in both assay methods. Extracts of a formulation containing plasticizer and a dioctyl tin mercaptide were toxic to both cell lines in the carboxyfluorescein assay but were only toxic to the WI38va13 cells in the MTT assay. The WI38va13 cells were generally more sensitive to the extracts than the HepG2 cells. When serial dilutions of the extracts were evaluated, the carboxyfluorescein assay proved to be the more sensitive of the two. The acute toxicity of extracts of these PVC formulations cannot be directly attributed to the plasticizers or to the tin stabilizers. It is likely that a synergistic mechanism, such as plasticizer facilitated extraction of the tin stabilizer, exists.

ISSN:0920-5063    

DOI:10.1163/156856295X00454

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor